Slovenian boatbuilder EJET is on a mission to prove that pure-electric yacht tenders can not only rival petrol-powered equivalents but potentially surpass them when it comes to power, performance and speed. That motivation has led to the production of EJET’s electric jet tender, the EJET 4X – soon to be followed by the larger EJET 9X model. The RIB’s design was developed in partnership with Ljubljana-based naval architect Jalen Vogelnik and yacht designer Andrej Justin.
“We’re witnessing a surge in demand from clients who not only prioritise sustainable yachting but aim to reinforce their commitment to an eco-friendly lifestyle through their choice of tender,” comments Žiga Jarc, CEO of EJET. However, he adds: “When it comes to electric boating, most often, people turn to the automotive industry for inspiration. We quickly realised that this approach comes with limitations.
“A boat presents a completely different challenge. The density of water is 830 times higher than that of air, which means it’s like constantly climbing uphill. This led to a host of problems that demanded a different approach.”
As a result, EJET specifically engineered the hull design of the 4X and 9X to fit around the jet drive, to maximise performance. The 4X incorporates an Alamarin-Jet system, running off a 60kW or 70kW pure-electric powertrain, removing the possibility of oil leaks or harmful emissions. The jet system is matched to an actuator control unit to enable reverse operations, even at high speeds. Combined with its optimised hullform, this arrangement grants the tender stable and smooth navigation at high speeds, and a range of up to 40nm.
Jarc tells Ship & Boat International: “The jet propulsion system stands out for its shallow draught compared to outboard or sterndrive options, making beach landings and exploration of hard-to-reach areas much easier”. The 4X is also fitted with a ski hook to enable waterskiing and wakeboarding.
The tender’s 7” touch display warns crew when battery power levels are low, of if the battery management system detects a problem
EJET has taken an interesting approach to the installation of the tender’s batteries. “We source our battery cells from a leading manufacturer and then build our own battery packs in-house,” Jarc explains. “This approach, though challenging, has allowed us to develop battery packs tailored specifically to our tenders in terms of shape, capacity and voltage. By taking control of this process, we’ve created packs significantly lighter than those used by our competitors.” Jarc estimates that the 4X is “100kg lighter than its nearest competitor”, while offering approximately 15% more battery capacity and delivering double the continuous power output from the electric motor. The boat’s custom powertrain is managed by an electronic control unit, offering driving modes such as ‘Eco’, ‘Normal’ and ‘Power’, which can be set via a 7” touch display.
If the battery management system (BMS) detects a low battery level, the 4X switches into ‘Eco’ mode to ensure a safe return to shore (or to the mother yacht). The BMS also alerts crew immediately, through the touch display, if issues arise. “We’re also developing a mobile app that will allow users to monitor the tender remotely and share data with us to prevent malfunctions before they occur,” Jarc reveals. Customers can specify a 6kW charger with a 9m portable charging cable, which will top up the batteries within eight hours. Alternatively, a 12kW charger enables fast-charging within four hours. The tender is also equipped with LED navigation lighting, for enhanced safety during night-time manoeuvres. “Optional underwater lights allow for night swimming,” Jarc adds.
The hulls on both the 4X and 9X models are constructed from GRP, and the tubes can be produced in white or black carbon. The upholstery aboard each tender type features water-resistant embossed patterns, while the deck is fashioned in Permateek, a synthetic, sustainable alternative to traditional teak. Customers can equip the boat with a Garmin Fusion sound system, and the tender comes with a contactless RFID key as another neat touch.
The EJET 9X, due for launch in Q1 next year, will be powered by a 223kWh battery
Next up is the launch of the first EJET 9X, scheduled for Q1 2025. This RIB will be powered by a 270kW electric engine, complemented by a dynamic 223kWh battery and a Hamilton jet drive – sufficient for a speed of 35knots, and extending the range to 50-60knots.
The 9X will be offered in two variants, with or without a rigid T-top, though Jarc says that the most notable feature will be its hydraulic stern platform, which can be adjusted to create “a small private beach”. He adds: “In the neutral position the platform is flat, but it can be raised or lowered thanks to a mechanism that turns it into steps, making access to the tender extremely easy.” Customers can use the extra space to install amenities such as an ice maker and a refrigerator. Beyond the 9X, EJET is also planning a 7m version of the tender.
If the 9X and future models sell as well as the 4X has, Jarc will be happy: EJET sold out its 2023 production slots for the 4X. “We aim to collaborate with yacht manufacturers who share our vision for a cleaner and more sustainable yachting industry,” he concludes. “One possible solution that we highly appreciate is the integration of solar panels into the mother yacht’s design, enabling the use of clean and renewable energy to power the yacht and charge the tender.
See Ship & Boat International September/October 2024 for the full technical particulars
